Now enlighten us with the etymology of "hermano".
Ehm... Ok ...
Well, it derives from Latin "frater germanus" which meant "germ/sprout brother" (I don't know if full brother is correct in English but I mean brother with the same mother and father, as opposed to half brother).
In reality, the qualifier germanus was broadly used to mean "of the same kin/race", and that's where the Germans and Germanic's name derived from.
It shares the same root as the English germ (germen in Spanish) meaning origin, as in the germ of an idea or a wheatgerm.
Other romance languages opted for the adaptation of the "frater" part (frère in French, fratello in Italian) instead of the germanus part.
And there was apparently one of my German teachers in high school bullshitting us by claiming the "ch" was unique to the German language. He may be right though that you shouldn't do drills teaching that sound as it's a surefire way to ruin your voice.
Well, he or she was shockingly wrong.
Apart from in Spanish and German, that sound exists in Arabic, Hebrew, Greek, Russian or Dutch (in Dutch more or less), and I'm sure that also in other languages I'm not aware of.
Every time you see a Greek word transcribed as "ch", it represents that sound ("chronos", for instance.)
The same aplies to the Russian transcription "kh".
EDIT: I've just realized that perhaps your teacher referred to the softer typically German "ch" sound, as in "ich" or "sicher." In that case maybe he/she was right.
I'll leave it here. By this point you've already figured I'm a language freak and that's enough embarrassment for one day.